1. Field of the Invention
The invention relates in general to an organic light emitting diode (OLED) panel and a method of forming a polysilicon channel layer thereof, and more particularly to an OLED display panel having a dopant atom not selected from the IIIA group and the VA group doped inside a polysilicon channel layer and a method of forming the polysilicon channel layer thereof.
2. Description of the Related Art
In the conventional process of manufacturing a low temperature polysilicon (LTPS) liquid crystal display (LCD) panel and an organic light emitting diode (OLED) display panel, typically the excimer laser annealing (ELA) technology is used to scan and melt an amorphous silicon (a-Si) layer to form the crystallization of a polysilicon layer. The polysilicon layer can be used as a channel layer of a thin film transistor (TFT) to improve the electrical performance of the TFT.
According to related literatures, there are two types of defects affecting the electrical performance of polysilicon TFT, namely, the grain boundary trap defect and the interface trap defect. The grain boundary trap defect mainly occurs during the process of melting the crystallization of an amorphous silicon layer to form a polysilicon layer. When the ELA technology is used to melt the amorphous silicon layer to form the crystallization of a polysilicon layer (the technology is referred as the ELA crystallization technology hereafter), the number of grain boundary trap defects and the number of interface traps are approximately equal to 1012 and 1011, respectively. It can be seen from the number of defects that the channel quality of the polysilicon layer is greatly affected by the grain boundary trap defects.
In terms of an LTPS LCD, despite defects occur to the channel layer of the high efficient TFT manufactured according to the ELA crystallization technology, the TFT, which is merely used as a switch element of pixels, still meets the requirements of the LTPS LCD.
However, when it comes to OLED display panel, the above negative effect of defects can not be neglected. In the active pixel matrix of the OLED display panel, each pixel TFT drives an organic electroluminescent device (OELD) having an anode, a cathode and an organic material layer by a current. The polysilicon layer manufactured according to the ELA crystallization technology has non-uniformed crystallization and defects, causing the channel layer of each TFT to have different characteristics. As a result, line mura would occur to the OLED display panel, largely deteriorating the display quality of the OLED display panel.